On Board Diagnosis
Research: Andrea Hieble / Andreas Sachse
The figure on top shows a Motronic with E gas, sequential injection, pre-catalyst and post-catalyst probe. In this example a 16-pole plug enables, in principle, anyone to carry out a check of the engine management system with a suitable scan tool. The data profundity depends on the work clearance.
How it works
OBD became possible among other things due to a post-catalyst lambda sensor (two-step finger sensor). Not only the final exhaust gas can be checked, but also the proper working of single cylinders by paced comparison with the pre-catalyst probe. (broad-band lambda oxygen sensor) Because of various regulations it was introduced first in vehicles produced for the American market (California). In Europe all newly registered petrol engine vehicles from the year 2000 onwards must have OBD, likewise all diesel vehicles starting in the year 2004.
Another, very important advantage is the possibility of changing the software. Qualities of the engine - even its performance - can be changed if you transmit new identity fields and new programmes via the OBD interface to the control device. "Chip tuning" is outdated because there is no chip to replace any more. Besides, the data can be transferred even on the road by (mobile) phone. It is just a matter of time, until this system will be transferred to all electronically controlled components on board.
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